Linux 下配置zookeeper集群

我们首先准备三台服务器，IP地址分别如下（前提是要先安装JDK）

192.168.100.101
192.168.100.102
192.168.100.103

1、配置主机名到IP地址的映射(此步骤不是必须的,我们可以直接在zk的配置文件中填写IP地址)，这样配置的好处是如果某个IP地址发生了变化，我们不需要重启zookeeper，直接修改主机对应的IP地址即可。

直接修改/etc/hosts文件，设置主机zoo-1映射到192.168.100.101，设置主机zoo-2映射到192.168.100.102，设置主机zoo-3映射到192.168.100.103

[root@localhost zookeeper]# vi /etc/hosts

然后在文件末尾追加

192.168.100.101 zoo-
192.168.100.102 zoo-
192.168.100.103 zoo-

这里的映射关系，保存后立即生效的。

2、在其中一台机器上安装zookeeper，下载zookeeper到zoo-1的机器上，此处使用的zookeeper-3.4.9，zookeeper下载解压后，修改配置文件即可使用。

[root@localhost zookeeper]# tar zxvf /usr/local/download/zookeeper-3.4..tar.gz /usr/local/soft/zookeeper

进入conf目录下，将zoo_sample.cfg复制一份重命名为zoo.cfg(zookeeper启动时默认寻找conf下名字为zoo.cfg的配置文件)

[root@localhost zookeeper]# cd /usr/local/soft/zookeeper/zookeeper-3.4./
[root@localhost conf]# cp zoo_sample.cfg zoo.cfg

修改zoo.cfg中的配置信息

[root@localhost conf]# vi zoo.cfg

修改配置文件信息如下

# The number of milliseconds of each tick
tickTime=
# The number of ticks that the initial
# synchronization phase can take
initLimit=
# The number of ticks that can pass between
# sending a request and getting an acknowledgement
syncLimit=
# the directory where the snapshot is stored.
# do not use /tmp for storage, /tmp here is just
# example sakes.
dataDir=/usr/local/data/zookeeper #zookeeper数据目录
# the port at which the clients will connect
clientPort=
# the maximum number of client connections.
# increase this if you need to handle more clients
#maxClientCnxns=
#设置集群信息,此处的zoo-x可以用ip地址代替
server.=zoo-::
server.=zoo-::
server.=zoo-::

创建zookeeper的数据目录，即我们zoo.cfg中的dataDir对应的目录

[root@localhost conf]# mkdir /usr/local/data/zookeeper

在dataDir目录中，创建一个名为myid的文件，并写入机器对应的数字值，比如我们是在zoo-1的机器上，就将该值设置为1，即集群中sever.1=zoo-1:2888:3888中server.后对应的数字。这是zookeeper用来识别是那一台集群机器的标识。

[root@localhost conf]# echo "" > /usr/local/data/zookeeper/myid 

此时我们集群中的一台服务器就配置好了

3、在其余两台机器上也安装zookeeper，可以通过scp命令直接拷贝文件即可。每个机器的都是用相同的配置信息。

[root@localhost conf]# scp -r /usr/local/soft/zookeeper/zookeeper-3.4./ root@192.168.100.102:/usr/local/soft/zookeeper
root@192.168.100.102's password: 

输入密码即可将对应的文件传输到要其他集群机器上。

注：此处唯一不同的地方是每个dataDir下的myid中的内容要按照zoo.cfg配置文件中的集群信息设置。比如：192.168.100.102对应集群中的server.2，所以在myid中写入2

到此为止，集群相关配置已经完毕了。下面就可以启动集群了

4、启动zookeeper集群

我的启动顺序是：zoo-1 -> zoo-2 --> zoo-3

[root@localhost zookeeper]# pwd
/usr/local/soft/zookeeper
[root@localhost zookeeper]# zookeeper-3.4./bin/zkServer.sh start
ZooKeeper JMX enabled by default
Using config: /usr/local/soft/zookeeper/zookeeper-3.4./bin/../conf/zoo.cfg
Starting zookeeper ... STARTED

这样表明zoo-1的服务器已经启动，同时在我们当前操作路径下回生成一个zookeeper的日志文件，zookeeper.out

[root@localhost zookeeper]# pwd
/usr/local/soft/zookeeper
[root@localhost zookeeper]# ll
总用量
drwxr-xr-x.      8月    zookeeper-3.4.
-rw-r--r--.   root root  10月  : zookeeper.out

文件中记录了集群的日志信息，当只启动zoo-1服务器的时候，日志中会出现异常，应为集群其他服务没启动，所以这个异常是没问题的。大概信息如下

[root@localhost zookeeper]# tailf zookeeper.out
    at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:)
    at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:)
    at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:)
    at java.net.Socket.connect(Socket.java:)
    at org.apache.zookeeper.server.quorum.QuorumCnxManager.connectOne(QuorumCnxManager.java:)
    at org.apache.zookeeper.server.quorum.QuorumCnxManager.connectAll(QuorumCnxManager.java:)
    at org.apache.zookeeper.server.quorum.FastLeaderElection.lookForLeader(FastLeaderElection.java:)
    at org.apache.zookeeper.server.quorum.QuorumPeer.run(QuorumPeer.java:)
-- ::, [myid:] - INFO  [QuorumPeer[myid=]/:::::::::QuorumPeer$QuorumServer@] - Resolved hostname: zoo- to address: zoo-/192.168.100.103
-- ::, [myid:] - INFO  [QuorumPeer[myid=]/:::::::::FastLeaderElection@] - Notification time out:
-- ::, [myid:] - WARN  [QuorumPeer[myid=]/:::::::::QuorumCnxManager@] - Cannot open channel to  at election address zoo-/192.168.100.102:
java.net.ConnectException: 拒绝连接 (Connection refused)
    at java.net.PlainSocketImpl.socketConnect(Native Method)
    at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:)
    at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:)
    at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:)
    at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:)
    at java.net.Socket.connect(Socket.java:)
    at org.apache.zookeeper.server.quorum.QuorumCnxManager.connectOne(QuorumCnxManager.java:)
    at org.apache.zookeeper.server.quorum.QuorumCnxManager.connectAll(QuorumCnxManager.java:)
    at org.apache.zookeeper.server.quorum.FastLeaderElection.lookForLeader(FastLeaderElection.java:)
    at org.apache.zookeeper.server.quorum.QuorumPeer.run(QuorumPeer.java:)
-- ::, [myid:] - INFO  [QuorumPeer[myid=]/:::::::::QuorumPeer$QuorumServer@] - Resolved hostname: zoo- to address: zoo-/192.168.100.102
-- ::, [myid:] - WARN  [QuorumPeer[myid=]/:::::::::QuorumCnxManager@] - Cannot open channel to  at election address zoo-/192.168.100.103:

接着启动zoo-2和zoo-3,全部启动完毕后，集群会自动选举出一台服务器作为leader，其余服务器为follower。

可以在每台服务器上使用命令查看服务器是什么类型的:

[root@zoo- zookeeper]# zookeeper-3.4./bin/zkServer.sh status
ZooKeeper JMX enabled by default
Using config: /usr/local/soft/zookeeper/zookeeper-3.4./bin/../conf/zoo.cfg
Mode: follower
[root@zoo- zookeeper]# zookeeper-3.4./bin/zkServer.sh status
ZooKeeper JMX enabled by default
Using config: /usr/local/soft/zookeeper/zookeeper-3.4./bin/../conf/zoo.cfg
Mode: leader
[root@zoo- zookeeper]# zookeeper-3.4./bin/zkServer.sh status
ZooKeeper JMX enabled by default
Using config: /usr/local/soft/zookeeper/zookeeper-3.4./bin/../conf/zoo.cfg
Mode: follower

通过上面状态查询结果可见，zoo-2是集群的Leader，其余的两个结点是Follower。可以通过客户端，连接到ZooKeeper集群上。对于客户端来说，ZooKeeper是一个整体（ensemble），你可以在任何一个结点上建立到服务集群的连接，例如：

[root@localhost zookeeper]# zookeeper-3.4./bin/zkCli.sh -server 192.168.100.101:
Connecting to 192.168.100.101:
-- ::, [myid:] - INFO  [main:Environment@] - Client environment:zookeeper.version=3.4.-, built on // : GMT
-- ::, [myid:] - INFO  [main:Environment@] - Client environment:host.name=localhost
-- ::, [myid:] - INFO  [main:Environment@] - Client environment:java.version=1.8.0_151
-- ::, [myid:] - INFO  [main:Environment@] - Client environment:java.vendor=Oracle Corporation
-- ::, [myid:] - INFO  [main:Environment@] - Client environment:java.home=/usr/local/soft/java/jdk1..0_151/jre
-- ::, [myid:] - INFO  [main:Environment@] - Client environment:java.class.path=/usr/local/soft/zookeeper/zookeeper-3.4./bin/../build/classes:/usr/local/soft/zookeeper/zookeeper-3.4./bin/../build/lib/*.jar:/usr/local/soft/zookeeper/zookeeper-3.4.9/bin/../lib/slf4j-log4j12-1.6.1.jar:/usr/local/soft/zookeeper/zookeeper-3.4.9/bin/../lib/slf4j-api-1.6.1.jar:/usr/local/soft/zookeeper/zookeeper-3.4.9/bin/../lib/netty-3.10.5.Final.jar:/usr/local/soft/zookeeper/zookeeper-3.4.9/bin/../lib/log4j-1.2.16.jar:/usr/local/soft/zookeeper/zookeeper-3.4.9/bin/../lib/jline-0.9.94.jar:/usr/local/soft/zookeeper/zookeeper-3.4.9/bin/../zookeeper-3.4.9.jar:/usr/local/soft/zookeeper/zookeeper-3.4.9/bin/../src/java/lib/*.jar:/usr/local/soft/zookeeper/zookeeper-3.4.9/bin/../conf:
2017-10-28 01:24:49,359 [myid:] - INFO  [main:Environment@100] - Client environment:java.library.path=/usr/java/packages/lib/amd64:/usr/lib64:/lib64:/lib:/usr/lib
2017-10-28 01:24:49,359 [myid:] - INFO  [main:Environment@100] - Client environment:java.io.tmpdir=/tmp
2017-10-28 01:24:49,359 [myid:] - INFO  [main:Environment@100] - Client environment:java.compiler=<NA>
2017-10-28 01:24:49,359 [myid:] - INFO  [main:Environment@100] - Client environment:os.name=Linux
2017-10-28 01:24:49,359 [myid:] - INFO  [main:Environment@100] - Client environment:os.arch=amd64
2017-10-28 01:24:49,359 [myid:] - INFO  [main:Environment@100] - Client environment:os.version=3.10.0-693.el7.x86_64
2017-10-28 01:24:49,359 [myid:] - INFO  [main:Environment@100] - Client environment:user.name=root
2017-10-28 01:24:49,359 [myid:] - INFO  [main:Environment@100] - Client environment:user.home=/root
2017-10-28 01:24:49,359 [myid:] - INFO  [main:Environment@100] - Client environment:user.dir=/usr/local/soft/zookeeper
2017-10-28 01:24:49,360 [myid:] - INFO  [main:ZooKeeper@438] - Initiating client connection, connectString=192.168.100.101:2181 sessionTimeout=30000 watcher=org.apache.zookeeper.ZooKeeperMain$MyWatcher@67424e82
2017-10-28 01:24:49,400 [myid:] - INFO  [main-SendThread(192.168.100.101:2181):ClientCnxn$SendThread@1032] - Opening socket connection to server 192.168.100.101/192.168.100.101:2181. Will not attempt to authenticate using SASL (unknown error)
Welcome to ZooKeeper!
JLine support is enabled
2017-10-28 01:24:49,544 [myid:] - INFO  [main-SendThread(192.168.100.101:2181):ClientCnxn$SendThread@876] - Socket connection established to 192.168.100.101/192.168.100.101:2181, initiating session
2017-10-28 01:24:49,560 [myid:] - INFO  [main-SendThread(192.168.100.101:2181):ClientCnxn$SendThread@1299] - Session establishment complete on server 192.168.100.101/192.168.100.101:2181, sessionid = 0x15f5ed84b260001, negotiated timeout = 30000

WATCHER::

WatchedEvent state:SyncConnected type:None path:null
[zk: 192.168.100.101:2181(CONNECTED) 0] ls /
[zookeeper]